Mount for electron discharge devices



April 12, 1938. 11A. STERNBERG. 2, ,9

- MOUNTFOR ELECTRON DISCHARGE DEVICES Filed June 27, 1934 INVENTOR ,Ffzg,i THEODORE A.-5TERNBER6 BY {725v arllllllrim I W %a%% 34 35- v 36 ATTORNEY Patented Apr. 12, 1938 MOUNT FOB ELECTRON DISCHARGE DEVICES Theodore A. Sternberg, Newark, N. 1., assignor to Radio Corporation of America, a corporation of Delaware Application June 27, 1934, Serial No. 732,553

zClaims.

My invention relates to improvements in elec-- tron discharge devices and more particularly to improved means for firmly and accurately positioning the electrode mount within the envelope of a. tube.

In modern tubes such as tubes having dome type bulbs or envelopes, it is found desirable to hold the electrode assembly firmly in place in the envelope to prevent transverse movement of the mount. To this end the dome or other constricted portion of the tube is utilized to steady the electrode assembly against transverse movement and to keep the assembly more firmly established in position than when the assembly is supported and steadied only from the stem press. The mount should be steadied sufilciently to avoid noises, such as clicking, due to contact between the electrode assembly and the envelope when the tube is jarred or vigorously vibrated. The

steadying means or mount spacer should be sufilciently resilient to avoid the stresses and distortion of the mount assembly produced when a mount with a rigid steadying means is forced into a bulb dome smaller than usual. Metallic spring spacers are resilient and easily made and attached to the mount, but the use of such metallic springs to steady the mount has not heretofore been favored because strain checks and cracks were often produced in the glass bulb during exhaust at the points where the metal touched the glass. It is theusual practice to attach to the mount, the mica mount spacers either in the form of a plate or disc extending transversely of the dome portion of the envelopeor in the form of vertical oblong shaped micas attached to the mount intermediate their'ends and with their ends in contact with the walls of the bulb. Mica mount spacers also have some disadvantages, as commercial mica varies from .008" to .020" in 0 thickness and the resiliency of the mica mount spacers varies considerably with the result that the mounts are not always positioned centrally oi the bulb. Attaching the vertical micas to the and engaging the interior walls of the bulb without injury to the mount during assembly or to the bulb during exhaust.

The novel features which I believe to be characteristic of my invention are set forth with par- 5 ticularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a partial view in perspective of one form of 10 an electron discharge device embodying my invention; Figure 2 is an enlarged horizontal cross section taken along line 2-2 of Figure 1; Figure 3 is an enlarged partial vertical section taken along lines 3-3 of Figure 2; Figure 4 is a par- 15 tial view in perspective of a modification of an. electron discharge device embodying my invention; Figure 5 is an enlarged horizontal cross section taken along the line 5-4 of Figure 4; Figure 6 is an enlarged partial ver- 20 tical section taken along line 6-6 of Figure 5; Figure '7 is a partial plan view of another modification of an electron discharge device embodying myinvention; Figure 8 is an enlarged vertical section taken along the line H of Figure 5 ,7; Figure 9 is a partial plan view of a still further modification of an electron discharge device embodying my invention and Figure 10 is an enlarged vertical section taken along line "-10 of Figure 9.

The electron discharge device shown in Figure i has a dome type of bulb it, which is provided with the usual stem press and base not shown. The amount ll comprises the usual electrode assembly and extends into the tubular-portion or 35 dome of the bulb Ill. The mount has secured to its upper end by straps l3, welded to the mount,

a sheet insulator or electrode spacer l2, preferably of mica, which may be of any shape but is shown as a hexagonally shaped plate in Figures 1, 2 and 3 and which extends transversely of the mount and of the tubular portion or dome of the envelope Ill.

In view of the fact that the envelopes are not all of exactly the same diameter, rigid mount spacers fastened to the upper end of the mount to fit snugly in the dome are not feasible. If the mount spacers are rigid and fit the largest envelope the mount will be stressed and distorted when a smaller envelope is placed over the mount assembly, while if the spacer fits the smaller envelope it will be loose in the large envelope and clicking will result.

In accordance with my invention I provide the mica plate l2 with resilient metallic spring spacers or fingers M, which are fastened to and extend radially from the edge of the plate [2 into contact with the inner wall of the dome ofvthe envelope ID to resiliently support and steady the mount and center it in the envelope.

These metallic spring fingers, which may be made for example of tungstenor molybdenum wire, may be fastened as best shown in Figure 3 at their inner ends to the mica, for example; by means of rivets II which extend thru the mica spacer i2. These spring fingers are formed with bowed outer ends which engage the interior wall of the tubular portion of the envelope. when the bulb is placed over the mount the spring fingers are flexed downwardly to an extent dependent on the inner diameter of the dome of the bulb.

These fingers resiliently center the mount from the walls within the envelope and prevent clicking of the tube.

I have obtained very good results with tungsten wire of 10 mil diameter measuring about 5 mm. in length from the point at which it was fastened to the mica to the bowed end portion which may be from 2% to 3 mm. in length. The wire was riveted to the mica at from 2% to 3 mm. from its edge. The mica was formed to provide a clearance of from 2 to 3 mm. between the edge of the mica and the wall of the envelope.

While I do not wish to be restricted to any particular theory, I believe that the success of the metal spring fingers made in accordance with my invention is due to the fact that they are of very small mass and do not absorb very much heat and are heat insulated by means of the mica plate to prevent conduction of heat to and from the mount. As a result the temperature of the spring differential between the two is practically neglis gible thus preventing the checks and cracks in the glass envelope which are apt to occur when metallic spring spacers are used. A large temperature differential is likely to occur when heat is rapidly conducted from the metallic spring mount spacers to the mount when heating the envelope, or by conducting heat to the spring spacers from the mount during the high frequency heat treatment of the mount.

In a modification shown in Figures 4, 5 and 6 the mica plate 20 has spaced around it, near its edge, slots thru which the metallic spring ribbon mount spacers 2| extend, the mount spacers being formed as best shown in Figure 6 to provide an inwardly extending tongue 22 and a folded reverse portion 23 for securing the spring spacers or fingers to the mica. Good results have been obtained by making the spring spacers of tinned steel, about .012" thick and .073" wide. Tungsten or molybdenum, for example, would also have suitable characteristics for use as spring mount spacers.

In the modification shown in Figures '7 and 8 the mica plate 25 is provided with oppositely disposed apertures such as 26 and 21, thru which the metallic spring element in the form of a ribbon 28 is threaded to secure the ribbon to the mica so that its ends extend beyond the edges of the mica and contact the interior walls of the tubular portion of the envelope to space the mount within this portion of the envelope.

As shown in the modification in Figures 9 and 10 the mica plate ill may be provided with oppositely disposed apertures II and 32 into which portions of the metallic spring elements or mount spacers 33 -and SI extend and are fastened together preferably by weldingat points II and II. The ends of the springs which extend over the edges of the mica and into contact with the wall of the bulb may also be welded together.

These metallic spring fingers are capable of providing for wider variations of bulb diameters than the usual type of mica spacer and are usually more easily made and attached to the mount and retain their resiliency during the sealing and high frequency treatment of the mount during the exhaust operation.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which'my'invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in'the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:-

1. An electron discharge device including an envelope having a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly positioned to extend into the tubular portion, a mica plate secured to the mount to extend transversely of the tubular portion of the envelope and having an aperture, a metallic ribbon spring having portions on opposite sides of said mica plate and a portion in said aperture to hold the portions on opposite sides of the mica plate in place on said plate with the end of said spring extending over and beyond the edge of said mica plate and between the edge of the mica plate and the wall of the envelope to contact the ,walls of the tubular portion of the envelope for resiliently steadying the mount within the tubular portion of the envelope.

2. An electron discharge device including an envelope having a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly positioned to extend into the tubular portion, a mica plate secured to the mount to extend transversely of the tubular portion of the envelope and having an aperture, a metallic spring having portions disposed on opposite sides of said mica plate and a portion in said aperture to hold the portions on opposite sides of the mica plate in place on the plate, one end of said spring being bent back against the mica and the free end of said spring extending over and beyond the edge of said mica plate and between the edge of the mica plate and the wall of the envelope to contact the walls of the tubular portion of the envelope for resiliently steadying the mount within the tubular portion of the envelope.

THEODORE A. STERNBERG. 

